Freezing rain or freezing drizzle can create an ice irregularity on the upper surface of an airplane wing while the airplane is in flight. The ice irregularity can lead to loss of control of the airplane, particularly if the irregularity forms aft of the leading edge protection devices (e.g. de-icing boots) and forward of the control surfaces (e.g. ailerons). Ice accumulation on critical airplane surfaces, arising from exposure to super-cooled large water droplets during flight, is suspected of causing power loss and engine damage in some instances. Accordingly, aircraft regulatory authorities are recommending that manufacturers be required to demonstrate that their airplanes are capable of operating safely in freezing rain/drizzle and mixed water/ice crystal atmospheric conditions, including warning flight-crews of super-cooled large water droplet accumulation on critical aircraft surfaces.